The U.S. State Department said late Monday it is "gravely alarmed" over reports of chemical attacks by the Syrian regime.

"The United States is gravely alarmed by continued allegations of the use of chlorine gas by the Syrian regime to terrorize innocent civilians, this time in Idlib province near Saraqib," it said in a statement.

Emphasizing that the attack is the sixth reported instance in the past 30 days in Syria, the State Department urged the international community to demand Syria cease using chemical weapons.

"We implore the international community to speak with one voice, taking every opportunity to publicly pressure the Assad regime, and its supporters, to cease its use of chemical weapons and hold those responsible accountable for these brutal attacks," the statement said.

The statement also said Russia ultimately bears responsibility for the victims in East Ghouta and countless other Syrians targeted with chemical weapons since Moscow became involved in Syria.

By shielding the Syrian regime from accountability, Russia has not lived up to its commitments, the State Department said, adding the use of chemical weapons by all parties in Syria must stop.

Located in northern Syria near the Turkish border, Idlib was declared a de-escalation zone according to a cease-fire agreement last May reached in Kazakhstan’s capital Astana.

The Syrian regime, however, has repeatedly violated the deal and has targeted residential areas in opposition-held no-tension zones like Idlib.

Controlled by anti-regime armed groups, the province has been under intense airstrikes for the past two months.

In January alone, 211 civilians were killed and 1,447 wounded.

Syria has been locked in a devastating civil war since March 2011, when the Assad regime cracked down on pro-democracy protests with unexpected ferocity.

While UN officials say hundreds of thousands of people have been killed in the conflict, regime officials say the death toll is closer to 10,000.